Washington • Senator-elect Mitt Romney said Wednesday that President Donald Trump’s firing of Attorney General Jeff Sessions should not affect the special counsel’s investigation into Russian interference in the 2016 election.

Trump on Wednesday jettisoned Sessions, whom the president has often criticized and considered firing for some time, in the wake of the midterm election that saw Republicans lose control of the House.

Romney, who will take office in January, praised Sessions in a statement but, in his first warning shot at Trump since Tuesday’s election, made clear that Robert Mueller’s probe of Russia and Trump’s team should continue.

“I want to thank Jeff Sessions for his service to our country as attorney general,” Romney said in a statement and a tweet. “Under Acting Attorney General Matthew Whitaker, it is imperative that the important work of the Justice Department continues, and that the Mueller investigation proceeds to its conclusion unimpeded.”

I want to thank Jeff Sessions for his service to our country as Attorney General. Under Acting Attorney General Matthew Whitaker, it is imperative that the important work of the Justice Department continues, and that the Mueller investigation proceeds to its conclusion unimpeded.

Whitaker, who was Sessions' chief of staff, will take over Sessions' duties.

Sessions sent a letter to the White House Wednesday, after a disappointing election for Republicans, offering his resignation at Trump’s request. Trump has repeatedly attacked Sessions for recusing himself from the Russia investigation and his resignation was expected post-midterm.

Whitaker himself has been critical of Mueller’s role as special counsel and has mused that instead of firing him – which could create a constitutional crisis – the Justice Department simply defund his office to the point he couldn’t continue.

As acting attorney general, Whitaker would supervise Mueller's probe.

Trump’s move brought a swift rebuke from Democrats and the president’s critics, some of whom likened it to then-President Richard Nixon ordering the firing of the Watergate special prosecutor and accepting the resignations of his attorney general and deputy attorney general when they refused to do so. And there were immediate calls for Whitaker to also recuse himself from overseeing the special counsel’s office.

“Given his previous comments advocating defunding and imposing limitations on the Mueller investigation, Mr. Whitaker should recuse himself from its oversight for the duration of his time as acting attorney general,” Senate Minority Leader Chuck Schumer said Wednesday.

Even some Republican senators stepped up to caution the White House that they wouldn't sit idly by if Trump attempted to thwart the Mueller investigation.

“The one thing this does make certain is that the Mueller investigation into Russian meddling in the elections will continue to its end, as it should, because no new attorney general can be confirmed who will stop that investigation,” tweeted Sen. Lamar Alexander, R-Tenn.

Sen. Susan Collins also warned against any attempt to derail the Mueller probe, “regardless of who is AG.”

It is imperative that the Administration not impede the Mueller investigation. I’m concerned Rod Rosenstein will no longer be overseeing the probe. Special Counsel Mueller must be allowed to complete his work without interference—regardless of who is AG.

Romney, a former Massachusetts governor and two-time presidential candidate, was a leader of the ‘never Trump’ movement in 2016. But during his successful campaign to take over the seat of retiring Sen. Orrin Hatch, R-Utah, Romney has said he will be an occasional critic of the president “when it is a matter of substantial significance.”

“Hopefully,” he said, “there will be few occasions where I will be compelled by conscience to criticize. But, as I have said throughout this campaign, I will call them like I see them.”

Utah Sens. Hatch and Mike Lee, both Republicans, offered praise for Sessions but didn’t address the question of how it would impact the Mueller investigation.

“Jeff Sessions has served effectively for two years as Attorney General, and I wish him well in the next chapter of his life,” Hatch tweeted.

HATCH on the resignation of Attorney General Jeff Sessions: “Jeff Sessions has served effectively for two years as Attorney General, and I wish him well in the next chapter of his life.” #utpolpic.twitter.com/GGJB2ndPnK

Lee said, “Jeff Sessions is a dear friend who has served our nation admirably as U.S. Attorney, a senator, and as Attorney General. I wish him well in the next chapter of his long and successful career.”

Jeff Sessions is a dear friend who has served our nation admirably as U.S. Attorney, a senator, and as Attorney General. I wish him well in the next chapter of his long and successful career.

U.S. Attorney for Utah John Huber also heralded Sessions' service as attorney general, saying he “reinvigorated and motivated federal, state and local law enforcement professionals to perform at the highest levels and produce results on behalf of their communities.”

Huber didn’t mention the ongoing special counsel probe in his statement, but signaled his own devotion to Trump’s criminal justice agenda.

“I look forward to working under the leadership of the next Attorney General, and will continue to pursue the rule of law priorities of President Trump,” he said.

Sessions had tapped Huber to launch an investigation of whether the FBI abused its authority in surveilling a former top aide to Trump during the 2016 campaign and whether federal officials should have probed deeper into allegations of Democrat Hillary Clinton’s ties to the sale of U.S. uranium rights to a Russian-controlled company.

Republican members of Congress had asked Sessions to investigate a raft of controversies involving Clinton, though some of the issues have been deemed dubious by fact checkers.